YK-11 is a synthetic steroidal selective androgen receptor modulator (SARM) with reported dual activity: partial agonism at the androgen receptor (AR) and inhibition of myostatin (a negative regulator of muscle growth). While widely discussed in research and bodybuilding communities, published scientific data on YK-11 remain limited compared to other SARMs such as RAD-140 and LGD-4033. This review summarizes its proposed mechanisms, potential applications, experimental dosing references, safety concerns, and provides a frequently asked questions (FAQ) section.
- Introduction
Selective androgen receptor modulators (SARMs) are being explored as alternatives to anabolic steroids for conditions such as muscle wasting, osteoporosis, and age-related decline. YK-11 is unique among SARMs for its proposed myostatin-inhibiting effect, which could amplify muscle growth beyond that seen with typical androgen receptor agonism. However, peer-reviewed research is scarce, and most available data are derived from cell studies and anecdotal reports.
- Mechanism of Action
Androgen receptor modulation: Acts as a partial agonist of the androgen receptor in muscle and bone.
Myostatin inhibition: In vitro studies suggest YK-11 increases follistatin expression, indirectly suppressing myostatin, thereby promoting muscle hypertrophy.
Steroidal backbone: Unlike most nonsteroidal SARMs, YK-11 has a steroidal chemical structure, more closely related to dihydrotestosterone (DHT).
- Research Findings
3.1 Muscle growth
In vitro data suggest YK-11 stimulates myoblast differentiation and inhibits myostatin signaling, potentially enhancing muscle growth.
Anecdotal reports claim rapid increases in lean body mass and strength, though controlled human studies are lacking.
3.2 Bone health
Limited preclinical evidence suggests potential positive effects on bone density, though less studied compared to other SARMs.
3.3 Comparison to SARMs
YK-11 differs mechanistically from SARMs like RAD-140 and LGD-4033 due to its steroidal structure and proposed myostatin inhibition.
Considered potentially stronger in anabolic effect but with more unknowns regarding safety.
- Typical Experimental Dosing
⚠️ Disclaimer: No standardized clinical trials exist. These values are based on anecdotal and research-community reporting, not medical guidelines.
Common research ranges: 5–15 mg per day orally.
Cycle duration (reported): 4–8 weeks in non-clinical contexts.
Stacking: Often reported in combination with other SARMs or compounds for experimental synergy.
- Safety & Limitations
Suppression: Likely to suppress natural testosterone production due to steroidal structure.
Liver impact: Potential hepatotoxicity risk since it is orally active and structurally steroidal.
Anecdotal side effects: joint pain, aggression, fatigue, liver strain.
Scientific data gap: Human and even animal trial data are extremely limited compared to other SARMs.
Regulatory status: Classified as a research chemical. Not FDA-approved; banned by WADA for athletic use.
- Conclusion
YK-11 is a unique SARM-like compound with potential dual activity as both an androgen receptor modulator and myostatin inhibitor. While it holds theoretical promise for enhanced muscle growth, the lack of clinical research and concerns about safety, suppression, and hepatotoxicity make it a high-risk compound. Current knowledge remains largely speculative, and YK-11 should be considered strictly experimental.
- References (sample)
Kanno Y, et al. (2011). Selective androgen receptor modulator YK-11 induces myogenic differentiation and inhibits myostatin activity. Biochem Biophys Res Commun.
Dalton JT, et al. (2013). Selective androgen receptor modulators in preclinical and clinical development. Endocr Rev.
Basaria S. (2010). Selective androgen receptor modulators: metabolic and clinical perspectives. J Endocr Soc.
- Frequently Asked Questions (FAQ)
Q1: What is YK-11?
A: YK-11 is a synthetic steroidal compound considered a SARM-like molecule with additional myostatin-inhibiting properties.
Q2: How does YK-11 differ from other SARMs?
A: Unlike nonsteroidal SARMs (RAD-140, LGD-4033), YK-11 has a steroidal backbone and is reported to inhibit myostatin, potentially enhancing muscle growth beyond androgen receptor activation alone.
Q3: Is YK-11 stronger than RAD-140?
A: Anecdotally, YK-11 is considered highly anabolic, possibly stronger than RAD-140 in promoting muscle mass, but with more unknowns and potential risks.
Q4: What are common research doses?
A: Non-clinical reports often cite 5–15 mg/day for 4–8 weeks. No standardized or approved dosing exists.
Q5: Does YK-11 suppress testosterone?
A: Yes. Due to its steroidal structure, YK-11 likely suppresses endogenous testosterone production significantly.
Q6: Is YK-11 toxic to the liver?
A: Potentially, yes. Being orally active and structurally similar to steroids raises concern for hepatotoxicity, though no formal toxicity studies exist.
Q7: Is YK-11 legal?
A: YK-11 is not FDA-approved, is sold as a research chemical, and is on the WADA prohibited list.
Q8: Has YK-11 been tested in humans?
A: No published human clinical trials exist. Current knowledge comes from in vitro studies and anecdotal self-experimentation.
⚠️ Note: This review is for educational and research purposes only. YK-11 remains an experimental compound with limited scientific validation.
